Conventionally, among wafer boat support tables that support a wafer boat having a plurality of posts from below, the posts being configured to arrange and support a plurality of wafers at intervals in a vertical direction, one that supports a bottom surface of the wafer boat at four support points is known. In such a wafer boat support table, locking structures formed at inner sides of the four support points are locked to an opening of the wafer boat having an annular ring-shaped bottom surface. Each of the support points supports the bottom surface of the wafer boat through support surfaces formed at outer sides of the support points while being into contact with the bottom surface of the wafer boat.
Further, a wafer boat support table having an annular ring-shaped support surface is known. Such a wafer boat support table having an annular ring-shaped support surface disperses a load to be applied to the support surface and also disperses stress to be imposed on a unit area.
In general, both a wafer boat and a wafer boat support table are often formed of quartz. Thus, in most cases, there is no difference in thermal expansion coefficients between the wafer boat and the wafer boat support table.
However, in recent years, in a semiconductor manufacturing process, a process is often performed using a wafer boat made of SiC in view of reducing rod mark particles. In this process, a wafer boat support table is formed of quartz so that the wafer boat made of SiC and the wafer boat support table made of quartz have different thermal expansion coefficients. This causes particles from a surface at which the wafer boat support table is brought into contact with the wafer boat, which may fail to meet the needs of the next-generation particle specification, in which a demand for higher specification is increasing.